I think everyone accepts he COULD be playing Trask, but there is no problem debating whether he SHOULD be playing Trask.

Until we know for sure, there is going to be debate and speculation and Trask is going to generate that when you consider Bill Duke already was Trask. He might have been a pointless Trask, but he was still Trask. Hoping that audiences won't remember that isn't exactly the best approach to filmmaking.

People wanting them to threw In teenage Cyclops,Jean,and Storm In 1973 would be an even bigger error than having Trask.As I have pointed out Trask In last stand was Trask In name only.His first name never mentioned and no Indication
of him being a scientist.It's not out of question they pull a Emma Frost and Moira Mactaggert with him as Trask In DOFP